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I need some help regarding a car that i have, which is a Patrol 4.8L turbocharged has been tuned with Haltech elite 2500.
First of all the car smokes incredibly during a ramp run on the dyno & the afr was perfectly tuned 11.8:1 another test at 12.5:2, the Lambda on board and on the dyno reads exactly the same, but the plugs are getting excessive black and after few runs the car starts missing due to the plugs.
I installed EGTs that the tuner requested & during ramp run the max diff was 40 degrees (860-900) between the cylinders.
We changed the plugs several times and several brands, ingition coils, injectors, camshafts, CAS, but nothing!
We did a test on low rpm high load (1500rpm with full throttle) afr was 14:7 and still smoke comes!
Is the smoke blue or black?
Blue smoke indicates burning oil, so you might have a ring, valve guide, or turbo bearing issue. Have you done a leak-down test? If you do have leakage, you can determine if it's coming from the Intake, Exhaust, or Rings by listening to the sound of air moving.
You mention your plugs are fouling. If you start with a new/clean plug, do a ramp run and cut the ignition at the top of the run, you will get a better confirmation of the mixture during the run. Perhaps you are over-fueling on the over-run condition (inertia dyno, or the idle condition). You might need a hotter plug, or to run leaner at idle.
Lastly, your exhaust system may be contaminated with rich running in the past, normally enough time at the proper mixtures will cure that.
Thanks for your reply David,
There are no any leakages , it started happening after we installed aftermarket cams & bigger turbo Garret G42.
ill do the test n reply u back.
the only time i see smoke like you describe is from the engine burning water or oil from somewhere. as David said blue-ish smoke is oil and also white smoke is generally coolant. The best method ive found is to pull all the plugs and put a scope camera down the plug holes and look at the top of pistons. they should be dry carbon black. wet and black indicates oil consumption and wet/clean-tops indicate water consumption. that will tell you which cylinders are suspect and an idea of what is going on.
other than that recent exhaust work or new pipes can smoke a bit if theyre fabricated. like a new custom down pipe etc .
try to think of what came apart when the new parts were installed and that can lead you to possible causes.
What color is the smoke? Is the wideband readout reliable? You are measuring in Afr and not lambda, maybe the wideband is set for the wrong fuel?
Just how much more lift does the camshaft have?
It is not unknown for the OEM valve stem seals to have relatively small clearance between them and the valve spring retainer (cap) and for aftermarket camshafts to have enough lift for the retainer to contact, and damage, the seal. Depending on the valve train design, there could be a fair amount of oil getting onto the valve stem and working past the guide - worse, the retainer may even be helping pump it down the guide.
Alternatively, it is possible, if you changed the valve spring that you damaged the stem seals, to a similar affect.
You also fitted a new turbocharger, some types require a restriction in the oil feed to avoid the oil supply to it overwhelming the seals, and letting oil into the intake or exhaust housing to be burned in the engine or produce a smoke screen, respectively. This could be further compromised if there is poor drainage back to the crankcase. If you remove the turbocharger, it should be quite obvious if oil is making it's way out past the seals.
I had the same issue after installing high profile camshafts with high valve lift. In the manual it was saying that special attention to oil seal to retainer clearance is required but i missed that part. Ended up with smoking engine no matter what. Had to adjust valve guides and increase oil seal to retainer clearance.
If the oil is coming from the Turbo, perhaps the problem is too much oil pressure. I recently learned about this oil pressure regulator for turbos: